The loudness levels of many audio signals vary in a manner that some listeners find objectionable. One example is the audio signal in many audio/video signals such as television signals. During a program segment of the television signal, the audio signal has a relatively lower loudness level. Viewers will tend to set the volume on their televisions (or other audio reproduction equipment) based on this relatively lower loudness level. During commercial segments, the audio level is often at a relatively higher audio level. Some television viewers find the higher loudness level annoying. Other examples include audio only signals, such as FM radio signals where some segments of a radio broadcast may have a higher volume level than other segments.
Accordingly, it is desirable to differentially control the audio loudness of different segments of an audio signal.